A cylindrical step selector for a stepped transformer can have, for example, a support structure which can be generally cylindrical and which surrounds an axis about which the selector shaft can be angularly shaped or rotated in increments. Fixed step contacts are provided in the wall of this structure and can be engaged by contact bridges forming movable contacts which can be brought into engagement with the fixed step contacts at a lower end. This shaft is supported in a journal of electrically insulating material which it supported at the lower end of the support structure by means of struts also of electrically insulating material.
A step selector of this type is described in Austrian patent document No. 162,527.
With this system, however, the journal formed for the lower end of the shaft has had less than satisfactory stability.